As the element housing package for housing the semiconductor element (hereinafter also referred to merely as a package), for example, a package described in Patent Literature 1 is known. The package described in Patent Literature 1 includes a package substrate (base body), via-holes (connection conductors) provided from an upper surface to a lower surface of a package substrate and a signal-line metallic thin film (a circuit conductor) provided on the lower surface of the package substrate. The package described in Patent Literature 1 is used by being installed on a mounting board.
Examples of a method of mounting the package on the mounting board include a method of bonding and fixing the package on the mounting board by pressing the package through a bonding member such as a brazing material. Additionally, as described in Patent Literature 2, it is also possible to cite a method of providing fixing members for screwing at four corners or a lower surface of a base body of a package for housing an electronic component and fixing the package on a mounting board by screwing.
However, in the case where the circuit conductor is provided on the lower surface of the base body as the package described in Patent Literature 1, displacement may occur in the circuit conductor at the time of mounting the package on the mounting board.
Specifically, there is a case where slight warping occurs in the base body in a manufacturing process of the package. When the package is pressed on the mounting board in the state where the warping occurs in the base body, the board may be deformed. Accordingly, the circuit conductor installed on the lower surface of the base body may be displaced to a position different from a desired position. As a result, there is a case where impedance matching becomes difficult between the package and the mounting board.